1. Field of the Invention
The present invention relates to a check sample of a deep-frozen product or a product whose keeping temperature or point, which is below ambient temperature, has to be checked.
It is used for checking the maintaining of the deep-frozen state of deep-frozen or frozen products, more particularly intended for human consumption and which must only be defrozen or thawed at the time of their consumption. It can also apply to the checking of the maintaining of the temperature of an unfrozen product, but whose keeping temperature, which is below ambient temperature, has to be carefully respected (e.g. medicaments, photographic films, etc.).
2. Discussion of the Background
It is known that it is dangerous to consume products which, when they have been partly or completely thawed, have undergone refreezing, no matter under what conditions this was carried out.
It is generally the manufacturer of deep-frozen products who packs them and who has the main responsibility with respect to the consumer. However, the forwarding agent or retailer are also responsible for maintaining the deep-frozen state of the products.
It is absolutely indispensable to check maintaining of the deep-frozen state of products supplied by a manufacturer or retailer form the time of their manufacture or packing up to the delivery to a purchaser. Each product generally undergoes, from its manufacture and up to its consumption, a number of different handling, storage and manipulation operations. All these stages are generally referred to as the "cold chain". This expression means that when one of the meshes of this chain is defective, the product must be looked upon as damaged and consequently unsuitable for consumption.
As the manufacturer is mainly responsible for respecting the integrity of the "cold chain", not only when the product has left the place of manufacture, but even when it is stored by the retailer, it is necessary for the said manufacturer to ensure that in no case, even outside his direct supervision, the temperature of the deep-frozen product, no matter whether or not it is in a pack, never exceeds a critical temperature threshold generally corresponding to the thawing temperature until it is received by the consumer. This temperature can vary as a function of the nature of the product. It is generally well below 0.degree. C. and is not necessarily constant.
The checking function exercised by the manufacturer can also be exercised by the retailer, but also and more particularly by the consumer, who must thus be able to refuse any product unsuitable for consumption.
During the manufacture of the frozen product and during the first stages of its distribution, e.g. in cold stores, the means for checking and maintaining the ambient temperature provide adequate guarantees for its being maintained in the deep-frozen state. However, during the final distribution stages, which will bring the product to the consumer, the diversity of the handling operations, the quantity of deep-frozen products, which may or may not be conditioned, can lead to thawing risks, although they may be only of a very short duration.
The putting into place of an effective infrastructure in distribution circuits makes it possible to check the temperature of the products therein. However, this infrastructure is not sufficient and it can advantageously be completed by check samples of the deep-frozen products located in the immediate vicinity of the latter or within a pack or packing surrounding the same. A check sample of this type is e.g. described in Swiss patent 416 148. This check sample comprises a case or envelope sealed in an inviolable manner and having a predetermined internal shape and within the said case a meltable object having a predetermined shape, which is at least partly different form the internal shape of the case and having a volume smaller than the internal volume of the latter. This object has a melting point equal to or slightly below the thawing temperature of the product. It is not possible to reconstitute the initial shape of the object following an even partial thawing of the product, which has led to an even partial melting of said object in the case and no matter what the subsequent refreezing conditions are for the product.
The major disadvantage of such a check sample is that it cannot provide information as to the extent of the possible thawing of the product and in particular the depth to which said product has been partly or completely thawed below the surface thereof. However, such information is particularly useful, because it may make it possible to establish the causes of the thawing and the duration thereof, as well as the thermal energy received by the product during thawing.
Thus, the thawing depth makes it possible to calculate the unfrozen product volume and therefore deduce therefrom the thawing period and the thermal energy received.
The thawing threshold temperatures are subject to risks which are not solely dependent on said temperature, but more specifically on said temperature and the time during which the said thawing threshold has been exceeded, or the said temperature and the thermal energy stored above the threshold temperature. It is not possible to determine these pairs of values with the known check sample.
The object of the invention is to obviate these disadvantages and in particular to provide a check sample of a deep-frozen product making it possible to indicate, not only the surface thawed state thereof, but also the depth therein to which the thawing has taken place, while providing much more precise information as to the time during which the thawed state temperature has been exceeded and as to the thermal energy stored by the product during said thawing. The check sample according to the invention also makes it possible to obtain much more precise information on the thawing, as a result of a better thermal conductivity between the product to be checked and the check sample. The invention also makes it possible to check that a keeping limit temperature has not been exceeded, even when it e.g. exceeds zero.
The invention relates to a check sample for a deep-frozen product comprising a case sealed in an inviolable manner, which is at least partly transparent, which has a predetermined internal shape and, within the said case, a meltable object having a predetermined shape, which is at least partly different from the internal shape of the case and having a volume smaller than the internal volume of the case, said object having a melting point equal to or below the thawing temperature or the temperature at which product is maintained, the initial shape of said object being impossible to reconstitute following an thawing state or even partial reheating of the product having led to an even partial melting of the object in the case, no matter what the subsequent product refreezing or cooling conditions, characterized in that said case comprises a first part made invisible and integral with the product or a pack containing the said product by packaging therein, a second visible part, which is integral with the first part, the object comprising a first portion at least partly filling the first invisible part of the case and a second portion having a shape which is at least partly different from the internal shape of the second visible part of the case, said second portion of the object having at least one transparent window for rendering visible the said object.
According to a first embodiment of the invention, the surface of the second part of the case projects beyond said pack or product.
According to a second embodiment of the invention, the second part of the case is at least partly contained in a recess belonging to the pack or product, extending towards the interior of said pack or product, said transparent window being visible from the outside of said pack or product.
According to a variant of each embodiment of the invention, the first and second portion of the object are separate and made from the same meltable material.
According to another variant of the embodiments of the invention, the first and second portions of the object are integral and made from the same meltable material.